Systems and methods for supporting or occluding a physiological opening or cavity

ABSTRACT

Implantable devices for placement at a cavity or opening such as an aneurysm are disclosed. The implantable devices, in a deployed condition, have a generally inverted U-shaped profile with a curved or angled framework support structure sized and configured for placement in proximity to tissue surrounding the opening and anchoring legs extending proximally from the framework structure sized and configured to contact the wall of a neighboring lumen at opposed locations. Occlusive and semi-occlusive membranes may be associated with the framework support structure and deployed over the opening to provide exclusion of the opening and flow diversion. Proximal anchoring segments providing additional lumen wall surface area contact for the implantable device following deployment may be incorporated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/161,032, filed on May 20, 2016, which is a divisional of U.S. patentapplication Ser. No. 14/618,969, filed on Feb. 10, 2015 (now U.S. Pat.No. 9,615,831 issued Mar. 11, 2017), which is a continuation of U.S.patent application Ser. No. 13/774,759 filed Feb. 22, 2013 (now U.S.Pat. No. 8,979,893 issued Mar. 17, 2015), which is a divisional of U.S.patent application Ser. No. 12/554,850 filed Sep. 4, 2009 (now U.S. Pat.No. 8,388,650 issued Mar. 5, 2013), which claims the benefit of priorityof U.S. Application No. 61/094,693 filed Sep. 5, 2008, the content ofwhich is incorporated herein by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to implantable structures forplacement in proximity to an opening or cavity in a physiologicalstructure, such as the neck of an aneurysm, using minimally invasivetechniques, and to methods of making and deploying such structures. Inone aspect, the implantable structures described herein contact andsupport tissue in proximity to the opening or cavity. In another aspect,the implantable structures are at least partially occlusive and, whendeployed across an opening in a physiological structure (e.g., aneurysmneck), provide flow diversion from the opening and may providesubstantial occlusion of the opening. The structures described areparticularly useful for placement at wide neck, terminal and bifurcationaneurysms.

BACKGROUND OF THE INVENTION

Surgical techniques for closing openings and repairing defects inanatomical lumens and tissues, such as blood vessels, septal defects andother types of physiological irregularities and defects, are highlyinvasive. Surgical methods for clipping aneurysms, for example, requireopening the skull, cutting or removing overlying brain tissue, clippingand repairing the aneurysm from outside the blood vessel, and thenreassembling tissue and closing the skull. Surgical techniques forrepairing septal defects are also highly invasive. The risks associatedwith anesthesia, bleeding and infection during and following these typesof procedure are high, and tissue that is affected during the proceduremay or may not survive and continue functioning.

Minimally invasive surgical techniques may alternatively be used toplace occlusive devices within or across an opening or cavity in thebody, such as in the vasculature, spinal column, fallopian tubes, bileducts, bronchial and other air passageways, and the like. In general, animplantable device is guided to a desired site through a deliverycatheter and may be pushed through an opening at the distal end of thedelivery catheter by a pusher mechanism, such as a pusher or deliverywire, thereby deploying the device at the desired site of intervention.Once the occlusive device has been placed at the desired location, it isdetached from the pusher mechanism without disturbing placement of theocclusive device or damaging surrounding structures.

Aneurysms are bulges in an artery wall, generally caused by a weakeningin the artery wall, that form an opening or cavity and are often thesite of internal bleeding and stroke. In general, the minimally invasivetherapeutic objective is to prevent material that collects or forms inthe cavity from entering the bloodstream, and to prevent blood fromentering and collecting in the aneurysm. This is often accomplished byintroducing various materials and devices into the aneurysm.

Various types of embolic agents and devices are used to reduce risks toa patient associated with the presence of an aneurysm. One class ofembolic agents includes injectable fluids or suspensions, such asmicrofibrillar collagen, various polymeric beads and polyvinylalcoholfoam. These polymeric agents may be cross-linked (sometimes in vivo) toextend the persistence of the agent at the vascular site. These agentsare often introduced into the vasculature through a catheter. Afterintroduction and at the site, the introduced materials form a solidspace-filling mass. Although some of these agents provide for excellentshort term occlusion, many are thought to allow vessel recanalizationdue to absorption into the blood. Other materials, such as hog hair andsuspensions of metal particles, have also been proposed and used topromote occlusion of aneurysms. Polymer resins, such as cyanoacrylates,are also employed as injectable vaso-occlusive materials. These resinsare typically mixed with a radiopaque contrast material or are maderadiopaque by the addition of a tantalum powder. Accurate and timelyplacement of these mixtures is crucial and very difficult. Thesematerials are difficult or impossible to retrieve once they have beenplaced in the vasculature.

Implantable vaso-occlusive metallic structures are also well known andcommonly used. Many vaso-occlusive devices are provided in theconfiguration of helical coils and are constructed from a shape memorymaterial that forms a desired coil configuration upon exiting the distalend of a delivery catheter. The purpose of the coil is to fill the spaceformed by a defect or injury and facilitate formation of an embolus withthe associated allied tissue. Multiple coils of the same or differentstructures may be implanted serially in a single aneurysm or othervessel defect during a procedure. Implantable framework structures arealso used in an attempt to stabilize the wall of the aneurysm or defectprior to insertion of filling material such as coils.

Techniques for delivering a vaso-occlusive device to a target sitegenerally involve a delivery catheter and a detachment mechanism thatdetaches the device, such as a coil, from a delivery mechanism afterplacement at the target sue. A microcatheter is initially steeredthrough the delivery catheter into or adjacent to the entrance of ananeurysm, typically aided by the use of a steerable guidewire. Theguidewire is then withdrawn from the microcatheter lumen and replaced bythe implantable vaso-occlusive coil. The vaso-occlusive coil is advancedthrough and out of the microcatheter and thus deposited within theaneurysm or other vessel abnormality. Implantation of the vaso-occlusivedevice within the internal volume of a cavity and maintenance of thedevice within the internal volume of the aneurysm is crucial. Migrationor projection of a vaso-occlusive device from the cavity may interferewith blood flow or nearby physiological structures and poses a serioushealth risk.

One type of aneurysm, commonly known as a “wide neck aneurysm” is knownto present particular difficulty in the placement and retention ofvaso-occlusive coils. Wide neck aneurysms are generally referred to asaneurysms of vessel walls having a neck or an entrance zone from theadjacent vessel that is large compared to the diameter of the aneurysmor that is clinically observed to be too wide to effectively retainvaso-occlusive coils deployed using the techniques discussed above.

The placement of coils, or other structures or materials, in theinternal space of an aneurysm or other defect has not been entirelysuccessful. The placement procedure may be arduous and lengthy,requiring the placement of multiple devices, such as coils, serially inthe internal space of the aneurysm. Longer procedures, in general,involve higher risks of complication from anesthesia, bleeding,infection, and the like. Moreover, because placement of structures inthe internal space of an aneurysm doesn't generally completely occludethe opening, recanalization of the original aneurysm is more likely tooccur, debris and occlusive material may escape from within the aneurysmand present a risk of stroke, vessel blockage or other undesirablecomplications. Blood may also flow into aneurysm and other blood vesselirregularities after the placement of embolic devices, which increasesthe risks of complication and further enlargement of the aneurysm.Furthermore, some aneurysms, vessels and other passageway defects arenot well-suited to placement of coils or other conventional occlusivedevices.

Devices for maintaining vaso-occlusive coils within an aneurysm navebeen proposed. One such device is described in U.S. Pat. No. 5,980,514,which discloses devices that are placed within the lumen of a feedvessel exterior to the aneurysm to retain coils within the aneurysmcavity. The device is held in place by means of radial pressure of thevessel wall. After the device is released and set in an appropriateplace, a microcatheter is inserted into the lumen behind the retainerdevice and the distal end of the catheter is inserted into the aneurysmcavity for placement of one or more vaso-occlusive devices. The retainerdevice prevents migration of occlusive devices from the cavity. Aremovable occlusion system for covering the neck of an aneurysm whileembolic material is delivered to the aneurysm is described in U.S. Pat.No. 5,928,260.

Another methodology for closing an aneurysm is described in U.S. Pat.No. 5,749,894, in which a vaso-occlusive device, such as a coil orbraid, has on its outer surface a polymeric composition that reforms orsolidifies in situ to provide a barrier. The polymer may be activated,e.g. by the application of light, to melt or otherwise to reform thepolymer exterior to the vaso-occlusive device. The vaso-occlusive devicethen sticks to itself at its various sites of contact and forms a rigidwhole mass within the aneurysm.

Devices for bridging the neck of an aneurysm have also been proposed.U.S. Patent Application Publication No. 2003/0171739 A1, for example,discloses a neck bridge having one or more array elements attached to ajunction region and a cover attached to the junction region and/or thearray elements. The array elements may comprise Nitinol alloy loops andthe cover may comprise a fabric, mesh or other sheeting structure.

U.S. Patent Application Publication No. 2004/0087998 A1 discloses adevice and method for treatment of a vascular defect in which twosheets, or a sheet and a strut structure function to secure thevaso-occlusive device and to occlude an opening. This patent publicationlists numerous biocompatible compositions and materials that may be usedin connection with the device to promote adhesion, fibrosis, tissuegrowth, endothelialization or cell growth.

U.S. Patent Application Publication No. 2004/0193206 A1 disclosesanother device for at least partially occluding an aneurysm including aplurality of elongate members configured to move relative to one anotherto transform the bridge between the delivery and deployedconfigurations. A two array bridge, in which a first array is deployedinside the aneurysm and a second array is deployed outside the aneurysmis also disclosed.

U.S. Patent Application Publication Nos. 2007/0088387 A1 and2007/01918844 A1 disclose methods and systems for repairing defects inphysiological lumens, such as aneurysms by placing occlusive deviceshaving closure structures covering the opening, when deployed, andanchoring structures contacting the inner aneurysm wall, or the parentvessel, or both. Septal defect closure devices are also well known. Suchdevices occlude openings, or septal defects, in the heart or thevascular system. Septal closure devices are disclosed, for example, inU.S. Pat. Nos. 6,077,291 and 6,911,037. Bronchial flow control devicesthat seal or partially seal a bronchial lumen are also known, see, e.g.,U.S. Pat. No. 7,011,094.

Systems currently used for the detachment of implantable devices afterplacement include mechanical systems, electrolytic systems and hydraulicsystems. In mechanical systems, the occlusive device and the pusher wireare linked by means of a mechanical joint, or interlocking linkage,which separates once the device exits the delivery catheter, therebyreleasing the device. Examples of mechanical systems include thosetaught in U.S. Pat. Nos. 5,263,964, 5,304,195, 5,350,397, and 5,261,916.In electrolytic systems, a constructed joint (generally either fiber- orglue-based) connects the pusher wire to the occlusive device and, oncethe device has been placed in the desired position, the joint iselectrolytically disintegrated by the application of a current or heat.An example of an electrolytic system is provided in U.S. Pat. No.5,624,449. In hydraulic systems, the pushing wire is connected to theocclusive device by means of a polymer coupling. The pushing wirecontains a micro-lumen to which the physician attaches a hydraulicsyringe and, upon the application of pressure using the syringe plunger,the hydraulic pressure forces the polymer joint to swell and break,thereby releasing the device. An example of a hydraulic system isdescribed in U.S. Pat. No. 6,689,141.

Despite the numerous devices and systems available for placing embolicmaterials in an aneurysm and for occluding physiological defects usingminimally invasive techniques, these procedures remain risky and theresults rarely restore the physiological structure to its normal,healthy condition. Challenges also remain in accurate positioning ofimplantable devices during deployment, preventing shifting or migrationof implantable devices following deployment, and preserving flow inneighboring vessels following placement of implantable devices. Methodsand systems of the present invention are directed, among other things,to reducing the length and complexity of minimally invasive proceduresfor supporting and occluding openings and repairing a lumen or tissuedefect, and to restoring a physiological structure, such as a bloodvessel, to its normal, healthy condition. Methods and systems of thepresent invention are additionally directed to providing implantabledevices for supporting and/or at least partially occluding an opening orcavity, such as an aneurysm, that are safely and conveniently deployableusing minimally invasive techniques, that reduce shifting and migrationfollowing placement, and that do not restrict blood flow in neighboringvessels following deployment.

SUMMARY

The present invention provides methods and systems for placing andanchoring an implantable structure at an opening in an internal lumen orcavity within a subject's body using minimally invasive techniques. Ingeneral, these systems and methods are used in connection with vascularabnormalities such as openings or cavities and are described herein withreference to their application to aneurysms and other types of bloodvessel defects. It will be appreciated, however, that systems andmethods of the present invention are not limited to these applicationsand may be employed in a variety of medical indications in whichplacement of structures at an opening or cavity in a physiological lumenor passageway or tissue is desired.

The implantable devices described herein are suitable for placement at acavity or opening that faces or is accessible from a neighboring lumenor passageway through which an implantable device may be delivered anddeployed, such as at the neck of a wide neck, terminal or bifurcationaneurysm. The implantable devices have a generally inverted U-shapedprofile with a curved or angled framework support structure sized andconfigured for placement in proximity to, and generally contacting, thetissue surrounding the opening or cavity, such as the neck of theaneurysm. The implantable devices additionally comprise at least twoanchoring legs extending (proximally) from the framework structure sizedand configured to contact the wall of a lumen, such as a neighboringblood vessel, that extends proximally from the opening. The anchoringlegs are generally sized and configured to extend for a distanceproximally along the lumen (e.g., parent vessel) sufficient to anchorproximal to the margins of the aneurysm. This is an important feature,because some aneurysms may fully encompass the lumen, rather thanprotruding from a radial section of the lumen.

Endoluminal and endovascular procedures are commonly used for placingimplantable devices and materials in many types of interventions. Anintravascular guide catheter is generally inserted into a patient'svasculature, such as through the femoral artery, and guided through thevasculature to, or approaching, a desired site of intervention.Additional delivery mechanisms and specialized catheters, such asmicrocatheters, pusher devices and the like, may be used to facilitatedelivery of various devices and accessories to the target site.Implantable devices are generally detachably mounted to a pusher ordelivery mechanism and navigated through the guide catheter to thetarget site, where they are deployed and detached from the deliverymechanism. The delivery mechanism is then withdrawn through the guidecatheter and additional devices, accessories, drugs or the like may bedelivered to the target site, if desired, prior to removal of the guidecatheter.

In general, implantable devices of the present invention are deliveredto a target site, such as in the neurovasculature, in a small diameter,constrained condition. In one aspect, the present invention providesimplantable device assemblies comprising an elongated, flexible deliverycatheter, at least one elongated, flexible delivery mechanism axiallymovable with respect to the catheter, and an implantable device in asmall diameter, constrained condition associated with a distal end ofthe delivery mechanism and mounted at or near a distal end of thedelivery catheter. The delivery mechanism may be a delivery (or pusher)wire or tube and may be detachably bonded to the implantable device ator near its distal end. In alternative embodiments, the deliverymechanism may be an expandable or inflatable device, such as a balloonthat facilitates placement and/or expansion of the implantable deviceduring deployment.

In another embodiment, the implantable device may be associated with adistal end of a delivery mechanism, such as a delivery wire, or multipledelivery wires, and an elongated, flexible introducer sheath providedover the delivery wire(s) and sized and configured for passage through aguiding catheter or a delivery catheter. The implantable device may bestored in a small diameter, delivery condition within a distal end ofthe sheath. In alternative embodiments, the implantable device may beassembled and stored in an expanded, deployed condition in a protectivecontainer, with a proximal end of the implantable device attached to thedelivery mechanism with the introducer sheath mounted over the deliverymechanism. In this embodiment, the implantable device is provided in adelivery condition by retracting the device into the distal end of thesheath prior to use.

The assembly is designed to be compatible with standard marketedendovascular delivery system technologies and can be loaded at theproximal catheter hub and then advanced the distance of the (alreadyplaced) guiding or delivery catheter, exiting the delivery catheter atthe target deployment site. Upon proper positioning at the targetdeployment site, the implantable device is advanced out of therestraining device in a controllable fashion and, as it exits therestraining device, the device assumes its larger diameter deployedcondition as it is positioned at the site. The device may be advancedusing one or more delivery wire(s) electrolytically, mechanically,hydraulically and/or thermally attached to the device and can beseparated from the device using electrolytic, mechanical, hydraulicand/or thermal techniques. Alternatively, the device may be advanced ordeployed using a pusher or a push/pull technique that requires nomechanical, hydraulic, thermal or electrolytic attachment method. Apusher may act as a pusher and/or a stabilizer for deployment of thedevice. The device may be partially or fully deployed, and detached ornot, depending on the application.

In the larger diameter deployed condition, implantable devices of thepresent invention comprise a generally inverted U-shaped, curved orangular framework support structure and at least two anchoring legsextending from the inverted U-shaped support structure alongsubstantially opposed planes. The inverted U-shaped support structure issized and configured for placement across the neck of an aneurysm andgenerally has a perimeter structure having a largest dimension at leastas large as the dimension of the aneurysm neck. The anchoring legs aresized and configured to extend proximally from the support structure andthe aneurysm neck following placement and deployment and contact thewalls of a neighboring vessel at generally opposed locations. In someembodiments, the anchoring legs extend from the framework supportstructure along substantially aligned, spaced apart planes. In someembodiments, implantable devices of the present invention compriseanchoring legs having a multi-dimensional configuration and, in adeployed condition, contact walls of a neighboring vessel at multiple,generally opposed locations.

In some embodiments, the framework structure forms a perimeter structurefor supporting an occlusive or semi-occlusive cover, or membrane,designed to restrict or inhibit flow into the cavity or escape ofmaterials from the cavity. In this aspect, methods and systems of thepresent invention may provide repair and reconstruction of a lumen, suchas a blood vessel, by placement and retention of a closure structureacross an opening or cavity to exclude the opening (e.g., aneurysm) fromthe parent artery and to divert blood flow away from the opening.Following placement and deployment, the closure structure maysubstantially cover the opening or cavity and form a structure thatsubstantially conforms to the tissue surrounding the opening and/or theneighboring lumen wall to restore the lumen to the configuration itwould assume in its healthy condition. Neither the anchoring structures,nor the support structure, nor the membrane interferes substantiallywith normal or desired fluid flow in the lumens in proximity to theopening.

Coverings and membranes including both occlusive and semi-occlusivematerials may be provided and supported by the framework structure.Occlusive and semi-occlusive coverings and membranes may incorporatepores or perforations and may have a variety of surface treatments. Theymay incorporate or be associated with a variety of materials to provideproperties desired for various applications. The inverted U-shapedframework structure is generally sized and configured to reside entirelyoutside the neck of the aneurysm following deployment. In someembodiments, the framework support structure may be associated with astructure extending distally for placement inside the aneurysm.

At least two anchoring legs extend from the inverted U-shaped frameworkstructure and, when deployed, contact the walls of a neighboringpassageway, such as the walls of the parent vessel of a terminal orbifurcation aneurysm with enough purchase to clear the aneurysm marginat substantially opposed locations. The anchoring structures aregenerally atraumatic and maintain the U-shaped framework structure inposition across the opening without damaging the neighboring tissue orrestricting blood flow neighboring vessel(s) or tissue. In a deployedcondition, the anchoring leg(s) extend proximally from the opening andthe framework structure and contact the wall of a lumen terminating inthe opening, such as a parent vessel. The anchoring legs thus supportthe framework structure and maintain it in position across the openingwithout occluding any bifurcating lumens or vessels and withoutoccluding the lumen terminating in the opening, such as the parentvessel.

The anchoring legs are generally formed integrally with or bonded to theinverted U-shaped framework support structure and extend proximally fromthe framework support structure when deployed, substantially oppositeone another. In some embodiments, the anchoring legs are symmetrical andeach anchoring leg has substantially the same configuration. Inalternative embodiments, the anchoring legs may have differentconfigurations, sizes, or the like. In one embodiment, the legs have agenerally tapered configuration, with a wider contact profile in thearea near the curved framework structure and a narrower contact profileas the legs extending proximally. In some embodiments, the anchoringlegs may form substantially planar structures aligned on substantiallyopposed, spaced apart planes. In other embodiments, the anchoring legsmay have a curved configuration that corresponds generally to the curvedconfiguration of the vessel wall and, following deployment, theanchoring legs are aligned substantially opposite one another contactingthe vessel wall.

In another embodiment, the anchoring legs, when deployed, extendproximally from the framework structure opposite one another to contactthe vessel wall in two opposed regions and additionally incorporateproximal extensions that extend away from the anchoring legs andterminate at locations where they contact the vessel wall in twodifferent opposed regions. The proximal extensions provide additionalsupport and additional vessel wall surface area contact for theimplantable device following deployment. In one embodiment, the distalextensions of the anchoring legs are formed by joining distal segmentsextending from opposed anchoring legs together at a circumferentiallocation intermediate the circumferential locations of the terminal endsof the anchoring legs. Anchoring legs incorporating proximal extensionsprovide at least four disparate circumferential vessel contact areas,arranged as two sets of generally opposed vessel contact areas atdifferent areas along the parent vessel. In one embodiment, theanchoring legs contact the parent vessel along contact areassubstantially opposite one another and the proximal extensions contactthe parent vessel along contact areas substantially opposite one anotherand proximal to and rotated approximately 90 degrees. from the anchoringleg contact areas.

Various agents, such as agents that promote re-endothelialization andtissue growth, as well as bonding agents, therapeutic agents,anti-thrombolytic agents, hydrophilic and/or hydrophobic agents, and thelike may be provided to the site during or following the placementprocedure and/or in association with the implantable device of thepresent invention. Exemplary agents that may be administered prior to,during or subsequent to device deployment, or may be associated with theimplantable device, are disclosed in U.S. Patent Application PublicationNos. 2004/087998 A1, 2004/0193206 A1 and 2007/0191884 A1, which areincorporated by reference herein in their entireties. It will also beappreciated that radiopaque markers or radiopaque compounds may beassociated with certain structures or portions of the implantable deviceand delivery assembly structure to facilitate accurate positioning,placement and monitoring of the device during and following deployment.

In one aspect, methods and systems of the present invention provideexclusion of a defect, such as an aneurysm, and diversion of blood flowaway from the aneurysm by placement of a framework structureincorporating a membrane that restricts access to and restricts orprevents flow communication between the vessel and the interior of theaneurysm across the neck of the aneurysm, and retention of the frameworkstructure and membrane across the opening by means of one or moreanchoring structures extending from the framework structure proximallyand contacting walls of a neighboring vessel, such as a parent vessel,in generally opposed regions. Methods and systems of the presentinvention may further promote shrinking and reabsorption of the defect,or portions of the defect, and facilitate hemostasis inside the defect.In one aspect, methods and systems of the present invention not onlyrestore the structure and function of the parent vessel in the vicinityof the defect, but also stabilize material inside the aneurysm, preventdebris from escaping into the bloodstream, and promote a reduction inthe size and mass of the aneurysm.

In some embodiments in which the implantable device that incorporates anocclusive or semi-occlusive cover associated with the frameworkstructure, systems and methods of the present invention are directed toproviding flow diversion and exclusion/occlusion of the cavity, such asan aneurysm, in a bifurcation or terminal aneurysm situation. In someembodiments, the implantable device may be utilized in combination withadjunctive devices such as endovascular helically wound coils, liquidembolic glues, stents and other agents that are deployed in a cavity oraneurysm prior to, during or following placement of the implantabledevice across the neck of the aneurysm. In these embodiments, theimplantable device may function to retain adjunctive devices within thecavity and may, optionally, also provide flow diversion from andocclusion of the cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a plan view of an implantable device of the presentinvention in a substantially flat, preassembled configuration.

FIG. 1B shows a schematic side perspective view of the implantabledevice of FIG. 1A in a folded, assembled configuration.

FIG. 1C shows a schematic side perspective view of an implantable deviceof the present invention incorporating a curved framework structuresupporting a cover and anchoring legs extending to form an implantabledevice having a generally inverted U-shaped profile.

FIG. 1D shows a schematic side perspective view of an implantable deviceof the present invention similar to the device shown in FIG. 1C buthaving a different anchoring leg structure.

FIG. 1E shows a schematic side perspective view of an implantable deviceof the present invention similar to the devices shown in FIGS. 1C and 1Dbut having a different anchoring leg structure.

FIGS. 2A-2F show schematic side perspective views of an implantabledevice having a configuration similar to that of the device illustratedin FIG. 1B in a small diameter delivery condition within a deliverycatheter (FIG. 2A), in various stages of deployment from the deliverycatheter at the site of a terminal aneurysm (FIGS. 2B-2D) and, detachedfrom the delivery mechanism(s) and in place across the neck of theterminal aneurysm (FIGS. 2E,2F).

FIG. 3A shows a schematic side, cut-away view of another embodiment ofan implantable device of the present invention deployed across the neckof a terminal aneurysm, and FIGS. 3B and 3C show an enlarged plan viewof alternative configurations of a portion of the device as indicated inFIG. 3A.

FIG. 4A shows a schematic plan view of another embodiment of animplantable device of the present invention in a substantially flat,unassembled configuration.

FIG. 4B shows a schematic side perspective view of the implantabledevice of FIG. 4A in a folded, assembled configuration, and FIG. 4Cshows a schematic side, cut-away view of the implantable device of FIG.4B deployed across the neck of a bifurcation aneurysm.

FIG. 5A shows a schematic side perspective view of another embodiment ofan implantable device of the present invention incorporating a contouredflow diversion membrane, and FIG. 5B shows a schematic side perspectiveview of another embodiment of an implantable device of the presentinvention incorporating a contoured flow diversion membrane.

FIG. 6A shows a schematic side perspective view of another embodiment ofan implantable device of the present invention, and FIG. 6B shows aschematic side, cut-away view of the implantable device of FIG. 6Adeployed across the neck of a bifurcation aneurysm.

FIG. 6C shows a schematic side perspective view of another embodiment ofan implantable device of the present invention, and FIG. 6D shows aschematic, side, cut-away view of the implantable device of FIG. 6Cdeployed across the neck of a bifurcation aneurysm.

FIGS. 7A and 7B show schematic side perspective views of alternativeembodiments of an implantable device of the present invention having analternative anchoring leg configurations providing flexing of theframework support structure with respect to proximal anchoring legs.

FIG. 8 shows a schematic side perspective view of another embodiment ofan implantable device of the present invention having an alternativeframework structure and cover configuration deployed across the neck ofa bifurcation aneurysm.

FIG. 9 shows a schematic side perspective view of another embodiment ofan implantable device of the present invention having an asymmetricalframework structure and cover configuration.

FIGS. 10A-10C show schematic side perspective views of the implantabledevice of FIG. 9 deployed across the neck of an aneurysm in differentconfigurations.

FIG. 11 shows a schematic side perspective cut-away view of anotherembodiment of an implantable device of the present invention deployedacross the neck of a terminal aneurysm.

FIGS. 12A-12D show schematic views of yet another embodiment of animplantable device of the present invention. FIG. 12A shows a plan viewof a device of the present invention in a substantially flat,pre-assembled form. FIG. 12B shows a side perspective view of thepre-assembled device of FIG. 12A in an assembled form. FIG. 12C shows afront cut-away view of the implantable device of FIG. 12B deployedacross the neck of an aneurysm, and FIG. 12D shows a side perspectivecut-away view of the implantable device of FIG. 12B deployed across theneck of an aneurysm.

FIGS. 13A-13G show schematic plan views of various embodiments offramework structures and cover membranes.

FIG. 14A shows a plan view of a device of the present invention in asubstantially flat, pre-assembled form having a perforated coverstructure and FIG. 14B shows an enlarged view of a portion of theperforated cover structure shown in FIG. 14A.

FIGS. 15A and 15B show enlarged schematic plan views of anchoring legterminal portions having mating configurations.

FIG. 16A shows a side perspective view of an implantable device of thepresent invention comprising a framework structure and anchoring legswithout a cover membrane, and FIG. 16B shows a side perspective view ofan implantable device having a framework structure similar to that shownin FIG. 16A with anchoring legs having a different configuration.

Like numbers have been used to designate like pares throughout thevarious drawings to provide a clear understanding of the relationship ofthe various components and features, even though different views areshown. It will be understood that the appended drawings are notnecessarily to scale, and that they present a simplified, schematic viewof many aspects of systems and components of the present invention.Specific design features, including dimensions, orientations, locationsand configurations of various illustrated components may be modified,for example, for use in various intended applications and environments.

DETAILED DESCRIPTION

In general, implantable assemblies of the present invention comprise animplantable device attached to at least one delivery wire or tube andloaded in a catheter or a sheath for delivery to a target site in ahuman body, such as in the neurovasculature at a site in proximity to awide mouth, termination or bifurcation aneurysm. The implantable deviceis delivered to the target site in a small diameter, constrainedcondition and is deployed, at the site, to its larger diameter deployedcondition. The device, in the deployed condition, comprises a generallyinverted U-shaped three-dimensional framework support structure having aperimeter structure configured to be positioned in close proximity to,and generally contacting tissue at the neck of the aneurysm along atleast a portion of its perimeter.

The framework support perimeter structure may incorporate substantiallyopposed lateral corners, or wing tip structures, lying on a longitudinalcenterline of the framework support structure that, when positionedacross the neck of an aneurysm, contact substantially opposed portionsof the aneurysm neck, or the vessel wall in proximity to the aneurysm,to support the opening. The generally U-shaped portions of the frameworkstructure extending on either side of a longitudinal centerline andbetween the lateral corners may be configured to contact portions of theneck of the aneurysm or circumferential areas of the vessel wall inproximity to the neck of the aneurysm when positioned across the neck ofan aneurysm. This implantable device configuration, when deployed,supports the neck of the aneurysm (and/or neighboring vessel wallsurface area) at lateral corners of the device and additionally supportsthe neck of the aneurysm (and/or neighboring vessel wall surface area)in radial, or circumferential, surface areas located between lateralcorner supports.

An occlusive or semi-occlusive closure structure, such as a meshstructure or a membrane, may be associated with the framework supportstructure to at least partially occlude the opening following placement.The closure structure, like the perimeter structure, may additionallyextend circumferentially on either side of and away from a longitudinalcenterline, and between the lateral corners, to contact portions of theneck of the aneurysm or radial or circumferential areas of the aneurysmneck and/or between the areas of wing tip contact. The closure structuremay fully or partially extend over the neck of an aneurysm followingdeployment.

The implantable device additionally comprises at least two discreteanchoring legs extending proximally from the framework support structurethat, in a three-dimensional deployed profile, form the terminal legs ofthe inverted U-shaped structure. The anchoring legs are configured tocontact the wall of a neighboring vessel, such as the parent vessel,following placement and deployment of the framework support structureacross the neck of an aneurysm. Several specific embodiments ofimplantable devices incorporating inverted U-shaped framework supportstructures and having at least two anchoring legs extending fromproximal regions of the framework structure are described with referenceto the figures.

The implantable device embodiments described in detail below areintended to be exemplary rather than limiting in nature. It is intendedthat component parts, structures and materials of construction describedherein with respect to specific embodiments may be used in connectionwith other embodiments incorporating other components andfunctionalities, as desired, to provide devices having appropriateconfigurations and functionalities for various and disparateapplications. A person having ordinary skill in the art will appreciatehow various of the components and structures herein may be combined toprovide yet additional devices and functionalities.

FIGS. 1A and 1B schematically illustrate an implantable device 10 of thepresent invention in a substantially flat, pre-assembled configuration(FIG. 1A) and in a three-dimensional deployed configuration (FIG. 1B).As shown, in FIG. 1A, implantable device 10 comprises a frameworkstructure having a generally diamond-shaped configuration formed byframework sides 11, 12, 13 and 14. In preferred embodiments, frameworksides 11, 12, 13 and 14 are joined at corners 15, 16, 17, 18, withlongitudinal centerline C_(L) extending between lateral corners 15 and16 and axial centerline C_(A) extending between axial corners 17 and 18.Framework sides 11, 12, 13 and 14, in the embodiment illustrated inFIGS. 1A-1E, form a perimeter structure and curve inwardly toward axialcenterline C_(A) in the area near the longitudinal centerline C_(L) inthe embodiment illustrated in FIGS. 1A and 1B, implantable device 10 isgenerally symmetrical with respect to both the longitudinal and axialcenterlines C_(L) and C_(A). In alternative embodiments, implantabledevice 10 may have an asymmetrical configuration with respect to eitherthe longitudinal or axial centerlines, or both.

While corners 15, 16, 17 and 18 are illustrated as being pointed, itwill be appreciated that the corners may have a curved profile, or amore complex curved or angular configuration. Framework sides 11, 12, 13and 14 may be formed integrally with one another, or separate frameworksides may be provided and bonded to one another at the corners. In oneembodiment, the implantable device framework structure is constructedfrom a substantially flat substrate by cutting, etching (or otherwise)the framework shape from a substantially flat substrate sheet. Theframework structure and anchoring legs may be constructed from materialhaving a substantially uniform thickness or, in alternative embodiments,the thickness of the framework structure and/or anchoring legs may vary.In one embodiment, for example, the thickness of the anchoring legs maybe greater in regions near their proximal terminus or junction.

Implantable device 10 may be assembled from the pre-assembled form ofFIG. 1A to the assembled form shown in FIG. 1B simply by bringing axialcorners 17 and 18, located on axial centerline C_(A), toward one anotherand forming a substantially inverted U-shaped framework structure withthe lateral corners 15, 16 located on longitudinal centerline C_(L)positioned at the “top” of the inverted U-shaped support structure inthe views shown in FIGS. 1B-1E, which is oriented distally during andfollowing deployment of the device. The longitudinal centerline C_(L) ispositioned substantially at the midline of the curved portion of theinverted U-shaped structure, while the axial centerline C_(A) generallybisects the device and joins axial corners 17, 18 forming the terminalends of the implantable device.

In this assembled configuration, implantable device 10 comprises aframework support having a perimeter structure formed by the frameworksides extending medially and radially from both lateral corners 15 and16 for some distance, such as to lateral marker 19, forming an invertedU-shaped structure when viewed from the end. The framework supportstructure is positioned distally during deployment, with at least aportion of the perimeter structure designed and configured to bepositioned in proximity to, and generally contact and support tissue inproximity to an opening or cavity such as an aneurysm. In particular,the framework support structure in proximity to lateral corners 15, 16aligned on longitudinal centerline C_(L) may provide contact points forcontacting the neck of an aneurysm or a vessel wall in proximity to theneck of an aneurysm during and following deployment of the implantabledevice. In some embodiments, wingtip extensions may be providedprojecting along the longitudinal centerline from the lateral corners toextend the reach of the framework support structure. The side wallsextending proximally and medially from longitudinal centerline C_(L) maycontact the neck of the aneurysm and/or the vessel wall medially andcircumferentially in the areas between the locations where the lateralcorners and/or the wingtip extensions contact the vessel wall.

Anchoring legs 20, 21 extend (proximally) away from the curved frameworksupport, forming the legs of the inverted U-shaped structure and, in theembodiment illustrated in FIG. 1B, form generally triangular structuresarranged substantially parallel to one another and spaced a distancefrom one another. Anchoring legs 20, 21 are generally atraumatic totissue and contact the vessel walls over an extended surface area.Following deployment, the corners 15, 16 of the framework supportstructure in proximity to the longitudinal centerline C_(L) form wingtipextensions that are positioned distally across the neck of an aneurysm,while the anchoring legs are positioned proximally to contact and besupported by walls of a neighboring vessel in proximity to the neck ofthe aneurysm, such as a parent vessel. This arrangement provides stablepositioning of the device across the neck of an aneurysm or anotheropening and reduces the possibility of device migration withoutinterfering with now in the associated and neighboring vessels.

FIG. 1C shows another embodiment of a generally inverted U-shapedframework structure having a configuration similar to that shown in FIG.1B but having an occlusive or semi-occlusive closure membrane 24associated with the substantially inverted U-shaped framework structure.In the embodiment illustrated in FIG. 1C, occlusive membrane 24 issubstantially co-extensive with the framework perimeter structure in theregion of and extending for some distance on both sides of longitudinalcenterline C_(L). Anchoring legs 20, 21 extend away from the frameworksupport structure and occlusive membrane 24, aligned substantiallyopposite one another. In the embodiment illustrated in FIG. 1C,anchoring legs 20, 21 are substantially planar structures and arealigned on substantially parallel, opposed planes. In alternativeembodiments, anchoring legs 20, 21 may be provided as curved structuresaligned substantially opposite one another and curving generallysymmetrically with respect to the axial centerline C_(A), generallymatching the curvature of a lumen or vessel. In yet alternativeembodiments, more than two discrete anchoring legs may be providedextending proximally from the framework support structure in a generallyradially symmetrical arrangement, providing multiple surfaces forcontacting multiple regions of the parent vessel.

Closure membrane 24 is generally designed to at least partially cover anopening such as an aneurysm neck and may have an irregular butsymmetrical configuration, as shown. Closure membrane 24 may completelyblock flow into or out from an aneurysm, or it may partially block flowwhen it has a porous or perforated structure or is constructed from apermeable material or covers a surface area smaller than that of theaneurysm neck.

FIG. 1D shows another embodiment of a generally inverted U-shapedframework structure having a configuration similar to that shown in FIG.1B, having an occlusive or semi-occlusive closure membrane 24 as shownin FIG. 1C, and also having anchoring leg extensions 26, 28. Anchoringleg extensions 26, 28 are formed integrally with or bonded to thecorners 17, 18, respectively, forming the terminal ends of anchoringlegs 20, 21. Anchoring leg extensions 26, 28 have a configurationdifferent from anchoring legs 20, 21 and may be simple linearextensions, as shown in FIG. 1D, or may take more complexconfigurations. Anchoring leg extensions 26, 28 are generally alignedsubstantially on the plane of the associated anchoring leg. In theembodiment shown in FIG. 1D, anchoring legs 20, 21 are associated with aporous or fibrous matrix material that is provided in openings inanchoring legs 20, 21 and promotes contact with and/or anchoring to avessel wall.

FIG. 1E shows another embodiment of an implantable device having astructure similar to that shown in FIG. 1C in a deployed conditionoutside a delivery catheter 30. In this embodiment, anchoring leg 21,terminating at corner 18, has an anchoring leg extension 28, whileanchoring leg 20, terminating at corner 17, is detachably mounted to adelivery mechanism in the form of delivery wire 32. The terminal ends ofeach anchoring leg may be identified and distinguished by differentlyconfigured radiopaque markers, illustrated as markers 33 and 34. Thisembodiment thus illustrates an implantable device having anchoring legstructures with different dimensions and configurations, and alsoillustrates an embodiment in which one of the anchoring legs isdetachably mounted to a delivery mechanism. One advantage of thisembodiment is that the device may be fully deployed into position withthe framework structure and closure membrane positioned across theopening of an aneurysm while the anchoring legs remain within thedelivery device and/or attached to the delivery mechanism. This providesflexibility for repositioning, retracting and redeploying theimplantable device prior to detachment from delivery wire 32.

The framework support structure and anchoring legs may be constructedfrom a variety of metallic materials, polymeric materials (e.g.polyethylenes, polypropylenes, Nylons, PTFEs, and the like), andcomposite materials. These components may be constructed, for examplefrom biocompatible stainless steels, from highly elastic metallicalloys, from biocompatible shape change materials that exhibitspseudo-elastic or super-elastic behavior and/or shape memory properties,such as shape memory alloys. The shape change material changes shape ina predictable manner upon application of a shape change force such asheat, current or the like, to assume its predetermined, deployedcondition. The force for producing the shape change is generally achange in temperature produced, for example, by introducing the deviceinto a body temperature environment, by applying heat to the deviceusing an external heating mechanism, or by heating the device byapplying current through a conductive element. Upon heating of the shapememory material to, or above, a phase transition temperature of thematerial, the device framework structure and/or anchoring structure(s)assume their predetermined, larger dimension configuration.

Nitinol alloys exhibiting super-elastic behavior are preferred for manyimplantable devices described herein and may be used to construct boththe framework support structure and the anchoring legs. In someembodiments, Nitinol alloys may also be used to construct a closuremembrane. When metallic materials such as Nitinol are used, frameworkand anchoring structures may be formed, for example, from solid wire,tubular wire, braided materials, or the like, and/or may be cut (oretched or otherwise removed) from substantially flat sheets of material,or from shaped substrate materials. Framework and anchoring structuresmay incorporate additional materials and may have coatings or membranesprovided between and among the framework structures and anchoring legs.In one embodiment, the framework and anchoring structures may be formedfrom a thin-film highly elastic alloy, such as a thin-film Nitinolalloy, using sputtering techniques that are known in the art. In anotherembodiment, described with reference to FIGS. 1A and 12A, the frameworkand anchoring structures may be constructed from a metallic or polymericor composite material by cutting, or etching, or otherwise providing apreassembled shape from a substantially flat sheet substrate andsubsequently shaping the preassembled shape to provide the desireddeployed conformation.

The occlusive or semi-occlusive membrane is generally constructed frommaterial(s) that are biocompatible and biostable and that arecompressible, foldable or otherwise deformable for assuming a lowdiametric profile in a delivery condition for loading into or mountingto a delivery catheter. Suitable membranes may comprise at least onelayer of flexible material and may have a substantially continuous,non-porous structure. Alternatively, occlusive or semi-occlusivemembranes may have various types of porous, perforated, woven, non-wovenand fibrous structures and may comprise multiple layers of material.

In one embodiment, the closure membrane is constructed from a materialthat is substantially impermeable to liquids such as blood and bodilyfluids. Alternatively, the closure membrane may be constructed from amaterial that is semi-permeable or permeable to liquids, such as bloodand bodily fluids, and allows at least limited fluid exchange across themembrane. Closure membrane 24 may be constructed, for example, from manytypes of natural or synthetic polymeric materials, polyurethanes,silicone materials, polyurethane/silicone combinations, rubbermaterials, woven and non-woven fabrics such as Dacron™, fluoropolymercompositions such as a polytetrafluoroethylene (PTFE) materials,expanded PTFE materials (ePTFE) such as and including TEFLON®,GORE-TEX®, SOFTFORM®, IMPRA®, and the like.

In another embodiment, the closure membrane may comprise a metallicmaterial, such as a thin-film shape memory alloy, e.g., a thin-filmNickel-Titanium alloy such as a Nitinol alloy or other biocompatiblemetals, including noble metals such as gold foils, tanalum wire and thelike. The membrane may be bonded, mechanically attached or fused to theframe to provide a secure seal and device strength. In some embodiments,the membrane and structural framework component may be constructed froma single piece of material such as Nitinol, stainless steel, silicone,Dacron, ePTFE, or another polymeric material.

In some embodiments, the closure membrane comprises a mesh-likestructure having a uniform or non-uniform configuration over its surfacearea. In general, closure membranes having a mesh configuration have agenerally fine mesh structure. In some embodiments, the membrane has amesh-like structure that is radially expandable. In other embodiments,the membrane has a mesh-like structure that is expandable along one ormore axes. The closure membrane, in some embodiments, is semi-permeableand has radial flexibility sufficient to mimic the structure andmovement (e.g. pulsatility) of the vessel wall or other physiologicalstructure it's repairing. When the implantable device incorporating theframework support structure and membrane is placed across the neck of ananeurysm, for example, it may become substantially continuous with andfollow the motion of the vessel wall, providing effective repair andreconstruction of the vessel wall and restoring strength, structure andflexibility to the vessel wall. In some embodiments, the frameworksupport structure and closure membrane, and/or anchoring structures,after placement across a tissue or vessel detect, not only effectivelyrepair the defect, but promote cellular ingrowth andre-endothelialization, thereby further incorporating the closure devicein the physiological structure and reducing the opportunity for thestructure to weaken and return to a structurally or functionallydefective condition. The framework support structure and/or membrane mayincorporate a reinforcing structure throughout its surface area, or inparticular areas of its structure.

The closure membrane may be associated with a reinforcing structurethroughout or at particular areas of its surface area. In oneembodiment, for example, a resilient and flexible sheet material may bebonded to or associated with a more rigid reinforcing structure having aregular or irregular pattern. The membrane may have a porous orperforated surface structure over at least a portion of its surfacearea, with pores arranged to provide a substantially uniform porosityover the surface area, or with pores arranged to provide differentporosities at different surface areas of the closure structure. Theaverage pore size may be substantially uniform over the surface area ofthe closure structure, or pores having different size distributions maybe provided. In general, pore sizes in the range of from about 0.5microns to 400 microns are suitable. In one embodiment, a pore structureis provided that permits flow of liquids across the closure structurebut excludes large proteins and cells, including red blood cells. Ingeneral, pores having an average diameter of less than about 10 micronswill exclude large proteins and cells, while allowing fluids topenetrate and cross the membrane. The arrangement of pores may form aregular or irregular pattern and the conformation of the pores may beuniform or non-uniform and may be generally circular, elliptical,square, or the like. A higher porosity may be provided, for example, atperipheral portions of the closure structure that, following placement,are in proximity to or contacting the tissue or vessel wall.

The membrane may, alternatively or additionally, have a surfacetreatment provided on one or both sides that promotes cellularattachment and growth. In one embodiment, for example, the membranematerial has a surface conformation that is irregular, or roughened, orincorporates surface irregularities that promote cellular attachment tothe material. In another embodiment, the closure structure may have athree dimensional configuration that incorporates depressions, grooves,channels, or the like, in a regular or irregular pattern, to promotecellular attachment and re-endothelialization.

In some devices disclosed herein, the membrane and/or other structuralcomponents of the implantable device, including one or more anchoringstructures, are structured or treated to promote, or comprise a materialor substance(s) that promotes, cellular ingrowth or attachment at thesite of deployment. Similarly, methods of the present invention mayinvolve introduction of agent(s) that promote cellular ingrowth andre-endothelialization at the site of the device deployment prior to,during, and/or subsequently to placement of the implantable device. Forvascular applications, for example, it is desirable for someapplications to promote the re-endothelialization of the blood vessel atthe site of an aneurysm or another vessel defect that may be repaired byplacement of devices of the present invention. Numerous substances thatmay be used in connection with methods and systems of the presentinvention are described in U.S. Patent Publications 2004/087998 A12004/0193206 A1, which are incorporated herein by reference in theirentireties.

Numerous materials may be administered prior to, during or subsequent todevice deployment, or associated with the implantable device, to promotecellular ingrowth. Biocompatible materials may be used for this purposeincluding, for example, proteins such as collagen, fibrin, fibronectin,antibodies, cytokines, growth factors, enzymes, and the like;polysaccharides such as heparin, chondroitin; biologically originatedcrosslinked gelatins; hyaluronic acid; poly(.alpha.-hydroxy acids); RNA;DNA; other nucleic acids; polyesters and polyorthoesters such aspolyglycolides, polylactides and polylactide-co-glycolides; polyactonesincluding polycaprolactones; polydioxanones; polyamino acids such aspolylysine; polycyanoacrylates; poly(phosphazines); poly(phosphoesters);polyesteramides; polyacetals; polyketals; polycarbonates andpolyorthocarbonates including trimethylene carbonates; degradablepolyethylenes; polyalkylene oxalates; polyalkylene succinates; chitin;chitosan, oxidized cellulose; polyhydroxyalkanoates includingpolyhydroxybutyrates, polyhydroxyvalerates and copolymers thereof;polymers and copolymers of polyethylene oxide; acrylic terminatepolyethylene oxide; polyamides; polyethylenes; polyacrylonitriles;polyphosphazenes; polyanhydrides formed from dicarboxylic acid monomersincluding unsaturated polyanhydrides, poly(amide anhydrides),poly(amide-ester) anhydrides, aliphatic-aromatic homopolyanhydrides,aromatic polyanhydrides, poly(ester anhydrides), fatty acid basedpolyanhydrides, and the like; as well as other biocompatible ornaturally occurring polymeric materials, copolymers and terpolymersthereof; fragments of biologically active materials; and mixturesthereof.

Some biocompatible polymers are considered to be bioabsorbable and aresuitable for use in association with devices and methods of the presentinvention, including polylactides, polyglycolides,polylactide-co-glycolides, poly anhydrides, poly-p-dioxanones,trimethylene carbonates, polycaprolactones, polyhydroxyalkanoates, andthe like. Biocompatible polymers which are not generally considered tobe biodegradable may also be used, including polyacrylates;ethylene-vinyl acetates; cellulose and cellulose derivatives includingcellulose acetate butyrate and cellulose acetate propionate; acylsubstituted cellulose acetates and derivatives thereof; non-erodiblepolyolefins; polystyrenes; polyvinyl chlorides; polyvinyl fluorides;polyvinyl (imidazoles); chlorosulphonated polyolefins; polyethyleneoxides; polyethylene glycols; polyvinyl pyrrolidones; polyurethanes;polysiloxanes; copolymers and terpolymers thereof; and mixtures thereof.Exemplary polymers are well known in the art and one of ordinary skillin the art would understand that such polymers are by far too numerousto list here. Thus, this list is intended for illustrative purposes onlyand is not intended to be exhaustive.

Non-polymeric materials may also be used on connection with membranesand implantable devices of the present invention. Suitable non-polymericmaterials include, for example, hormones and antineoplastic agents.Examples of other biocompatible materials that promote integration withthe vasculature of the patient include, for example, processed human oranimal tissue including, for example, cells or cell fragments,engineered vascular tissue, matrix material from bladder, stomach,liver, genetic material of a natural or synthetic origin, and the like.

Other types of compositions may also be associated with a membrane,framework structure and/or anchoring structure(s) forming theimplantable devices of the present invention. Hydrophilic and/orhydrophobic agents or bonding agents may be provided on all or a portionof the structure(s), for example. Similarly, friction-reducing agents,including fluoropolymers such as PTFE, may be provided on all or aportion of the structure(s) to facilitate deployment from a deliverycatheter or sheath. Radiopaque markers or radiopaque compounds may beassociated with certain structures or portions of device structure tofacilitate accurate positioning, placement and monitoring of thedeployed device. In one embodiment, for example, a radiopaquecomposition may be incorporated in the closure structure or provided asa coating on the closure structure. In yet another embodiment, certaintherapeutic agents, antibiotic agents, thrombogenic agents,anti-thrombogenic agents, and the like may be associated with certainstructures or portions of the device structure, or may be administeredprior to, during or following deployment of the implantable device.Suitable agents are well known in the art and are used in connectionwith other types of implantable devices.

The membrane may comprise multiple layers and may have a variety ofcoatings or other materials associated with it, such as adherent orbonding substances, therapeutic substances, hydrophilic or hydrophobicmaterials, swellable materials such as hydrogels, radiopaque markers,and the like. In one embodiment, for example, a swellable hydrogel maybe provided on a surface of the closure structure and/or anchoringstructures that, in a deployed condition, face or contact an internalportion of an aneurysm. In another embodiment, an agent or combinationof agents that promote embolization or thrombosis may be provided on asurface of the membrane, framework support structure and/or anchoringstructures that, in a deployed condition, face or contact an internalportion of an aneurysm to promote embolization inside the aneurysm. Inyet another embodiment, an agent or combination of agents that reducethrombosis and dotting, such as heparin, tissue plasminogen activator(tPA), Abciximab, and the like may be provided on a surface of theclosure structure and/or anchoring structures that, in a deployedcondition, face or contact a blood vessel or blood vessel wall. In stillanother embodiment, an agent or combination of agents that preventrestenosis and/or reduce inflammation to the site, such as Paclitaxel ora derivative or analog, Sirolimus, anti-inflammatory compositions suchas steroids, statins, ibuprofen or the like, may be provided on asurface of the closure structure and/or anchoring structures. In yetanother embodiment, a radioactive composition may be associated with asurface of the closure structure and/or anchoring structures fortherapeutic or imaging purposes.

The membrane associated with the framework support structure placedacross the neck of the aneurysm may have an opening or slot for passageof a guidewire of another delivery or targeting mechanism, or forintroduction of compositions, devices, or the like subsequent toplacement of the closure system. According to some methods of thepresent invention, additional embolic devices such as coils, liquid orparticulate embolics, or the like, may be introduced through a deliverycatheter inserted through an opening of the closure structure followingplacement of the closure structure.

The material(s) forming the membrane may be designed to incorporatevarious agents and/or coatings homo- or hetero-geneously provided acrossone or all layers to promote or retard cell growth, depending on thecharacteristics desired. For example, the inside surface of the coveringmay be coated with an agent to prevent excessive cell growth that mayblock the lumen of the vessel (i.e. to prevent restenosis), while theouter surface of the covering may be coated with a material designed topromote a healing response. In other embodiments, specific portions orsections of individual coverings may be coated or provided withmaterials having different properties.

Radiopaque markers may be incorporated into the design to position thedevice accurately in the vasculature. Variations in the marker geometrymay be adopted to distinguish different segments of the deviceframework. For example, the proximal legs of the device may incorporatea marker with two dots, while the portion of the device closer to or inproximity to the covering may incorporate a single dot. Alternatively,different shaped markers may be used to differentiate different parts ofthe device. Radiopaque markers may be added anywhere along the deviceframe or attached materials, coverings, and membranes to provide spatiallocation of different device components and features under angiography.

Numerous specific implantable device embodiments are described below. Itwill be appreciated that the disclosure provided above with respect tomaterials and modes of construction, the structure of the framework andmembrane components, the provision of radiopaque markers and otherfeatures as described above may be incorporated, as well, in thespecific embodiments described below.

FIGS. 2A-2F show schematic drawings illustrating the transition of animplantable device of the present invention from a small diameter,folded delivery condition inside a distal end of a delivery catheter(FIG. 2A) to a larger diameter, deployed condition implantable devicehaving the framework support structure positioned across the neck of ananeurysm and the anchoring legs positioned contacting the walls of aneighboring blood vessel, such as the parent vessel (FIGS. 2E, 2F).Framework structures, closure membranes and anchoring legs are foldableand deformable for delivery using a small diameter catheter, yet providestructural integrity, durability and a substantial degree of rigidity ina larger diameter, deployed condition.

In one embodiment, the framework structure, the closure membrane and theanchoring structures are generally radially compressed along thedelivery axis and arranged in a substantially cylindrical, deliveryconfiguration in a delivery catheter. In another embodiment, theimplantable device may be stored in a protective container in anexpanded, deployed condition, with the delivery mechanism (e.g. deliverywire or tube) packaged in hoops, as is known in the art. A loadingsheath may be provided, into which the implantable device is loaded toassume a smaller diameter delivery condition prior to being transferredto a delivery catheter for navigation to the target deployment site.

In embodiments that utilize a pusher system, the pusher is associatedwith a proximal end of one or both of the anchoring devices and cantranslate the closure device in relationship to the delivery catheter.Deployment may be achieved by a combination of actively pushing thedevice out of a delivery catheter and actively withdrawing the deliverycatheter while maintaining the device in a stationary condition. In analternative embodiment, implantable devices incorporate a detachmentelement that is released or detached following deployment. Detachmentmechanisms known in the art, including mechanical, electrolytic,hydraulic, thermal and other systems, may be utilized for deployment ofthe implantable devices disclosed herein.

FIG. 2A shows framework structure 40 and anchoring legs in a smalldiameter, delivery condition mounted near the distal end of deliverycatheter 45. The lateral corners 41, 42 of the framework structure 40are positioned distally in the delivery condition. In one embodiment, aproximal end of each of the anchoring legs is detachably mounted to anindependent delivery wire. Independent delivery wires may be joinedproximally of their detachable mounting to anchoring legs at a commondelivery wire 49 that extends proximally for the length of the deliverycatheter.

FIG. 2B shows a distal end of delivery catheter 45 positioned inproximity to the neck of aneurysm A formed at an end of a neighboringvessel, such as parent vessel (PV) where two side branch vessels SB₁ andSB₂ diverge. The delivery wires and delivery catheter 45 have been movedwith respect to one another to initiate the deployment of the frameworkstructure 40. In the initial stages of deployment, the lateral corners41, 42 aligned on the longitudinal centerline C_(L) of the frameworksupport structure project from the distal end of delivery catheter 45and expand laterally toward their deployed configuration. The membranestructure 24, if one is employed, is deployed and positioned across theneck of the aneurysm as the lateral corners expand to their fullydeployed position. Deployment of this device, including both theframework support structure and anchoring legs, is generally smooth andconsistent as the tapered framework legs and anchoring legs are easilyand smoothly pushed from the distal end of a sheath or deliverycatheter.

As the deployment proceeds, as shown schematically in FIGS. 2C and 2D,the delivery catheter is moved proximally along parent vessel PV andlateral corners 41, 42 of the framework support structure expand totheir fully deployed configuration. The implantable device ispositioned, as shown in FIG. 2D, with at least lateral corners 41, 42aligned on the longitudinal centerline C_(L) positioned to contact thetissue in proximity to the neck of the aneurysm. Anchoring legs 43, 44are deployed generally opposite one another along surface areas of theparent vessel to support and retain the implantable device in place.

In the deployed condition, as illustrated in FIGS. 2E and 2F, the distalportion of the inverted U-shaped framework support structure ispositioned across the neck of the aneurysm, with lateral corners 41, 42of the framework support structure positioned in proximity to, andgenerally contacting, tissue in proximity to the neck of the aneurysm.Depending on the size and configuration of the implantable device andthe size, position and character of the aneurysm, the aneurysm neck andthe adjoining vessel wall, the lateral corners of the frameworkstructure may extend to contact more or less tissue of the aneurysm neckand adjoining vessel wall. In some embodiments, the perimeter of theframework structure may be larger, in all areas, than the neck of theaneurysm and the entire perimeter of the framework structure may contactthe neck of the aneurysm or vessel wall following deployment. In otherembodiments, the framework corners or associated wingtip extensionsaligned on the longitudinal centerline C_(L) and regions of theperimeter structure in proximity to the framework corners contact tissueat or near the aneurysm neck following placement and deployment, whileother portions of the framework perimeter are unsupported by, orpositioned internally of the neck of the aneurysm following deployment.

In the embodiments illustrated in FIGS. 2E and 2F, the invertedsubstantially U-shaped perimeter support structure and associatedclosure membrane 24 substantially cover the neck of the aneurysm andextend circumferentially to contact tissue surrounding both sides of theneck of the aneurysm, or the vessel wall adjacent the neck of theaneurysm, at locations between the lateral corners and proximal to thelongitudinal centerline C_(L) of the device. In the embodimentsschematically illustrated in FIGS. 2E and 2F, for example, areas of theperimeter support structure and closure membrane 24 proximal to thelongitudinal centerline C_(L) and distal to anchoring legs 43, 44generally contact and support tissue, including the vessel wall, locatedcircumferentially of and in proximity to the neck of the aneurysm.Anchoring legs 42, 44, including proximal extensions, contact the wallof a neighboring vessel, such as parent vessel PV, to anchor and supportthe curved framework support across the neck of the aneurysm.

As shown schematically in FIGS. 3A and 3B, perforating vessels andsidebranches (shown schematically as P₁-P₆) often develop near aneurysmlocations. An implantable device 50 having a porous covering 54 may beadvantageously deployed in this circumstance to preserve flow in theperforating vessels and side branches. In some applications, it may beadvantageous to vary the porosity across the surface area of thecovering. An area that primarily covers the neck of the aneurysm A, forexample, may nave lower porosity (e.g., fewer pores, lower pore density,smaller pores, etc.) than an area that overlaps the neck of the aneurysmand contacts a vessel wall (SB₁, SB₂) in the area of the aneurysm neck.This may be accomplished, for example, by varying the pore size and/orspacing of the pores, to promote maintenance of patency of perforatingvessels P₁-P₆ near the aneurysm neck. FIG. 3B illustrates a section ofporous covering 54, wherein the pore density in the region near lateralcorner 52, where the framework support perimeter structure contacts theaneurysm neck or vessel wall, has a higher pore density than momcentrally located portions of closure membrane 54.

In alternative embodiments, very large pores or openings may be providedin areas where the framework support perimeter structure contacts theaneurysm neck or vessel wall. In the embodiment schematicallyillustrated in FIG. 3C, for example, closure membrane 54 does not extendto lateral corner 52 of the framework support perimeter structure, butterminates a distance from corner 52, leaving an opening 56 in theframework support perimeter structure that facilitates flow and reducesocclusion of perforating vessels. In this embodiment, the closuremembrane may be sized and configured to extend to the edges, or justpast the edges, of the aneurysm neck, while the lateral corners, orwingtip extensions of framework support structure may be sized andconfigured to extend further, providing support and contact along thevessel wall for a distance away from and in proximity to the neck of theaneurysm.

FIGS. 4A-4C schematically illustrate another embodiment of animplantable device 80 of the present invention. FIG. 4A showsimplantable device 80 in a substantially flat, pre-assembledconfiguration, while FIG. 4B schematically shows the device of FIG. 4A.In a three-dimensional, inverted U-shaped deployed condition, and FIG.4C schematically shows the device of 4B in a deployed condition acrossthe neck of an aneurysm A. Implantable device 80 comprises a frameworksupport structure 82 having a generally diamond-shaped configuration ina pre-assembled, flat condition, as shown in FIG. 4A. In thisembodiment, the framework sides join in the region of longitudinalcenterline C_(L) at a widest portion of the framework perimeter supportstructure and taper to form anchoring legs 84, 86. A closure membrane 85is formed integrally with or mourned to the framework support structureand extends for a distance on both sides of longitudinal centerlineC_(L).

Implantable device 80 may be constructed from the pre-assembled form ofFIG. 4A to the assembled form illustrated in FIG. 4B simply by foldingthe device along longitudinal centerline C_(L) and bringing the terminalends of anchoring legs 84, 86 toward one another to provide thesubstantially inverted U-shaped configuration illustrated in FIG. 4B. Inthe assembled configuration, the framework support structure and closuremembrane 85 form a curved, inverted U-shaped structure, while anchoringlegs 84, 86 extend proximally from the curved framework supportstructure along substantially parallel planes spaced a distance from oneanother.

The framework support structure and closure membrane of implantabledevice 80 additionally present a shaped, curved leading surface 88configured to engage the anatomical structure of the neck of aneurysm A,and to provide a more precise fit of the leading surface across the neckand opening of the aneurysm. Leading surface 88 has a generally concavecurved, saddle-shaped configuration along the longitudinal centerlineC_(L) with the elevated portions of the curved structure positionedgenerally in proximity to the framework perimeter structure. While thecurved configuration is illustrated as being generally symmetrical withrespect to the axial centerline C_(A) of the implantable device, it willbe appreciated that non-symmetrical curves may be desirable forparticular applications. In some embodiments, the curved leading surfacemay take the form of a convex curve, while in other embodiments, complexcurves, such as curves having hyperbolic paroboloid structures, may beused and may involve extend over larger regions of the frameworkstructure and/or closure membrane. Implantable devices having thiscurved configuration may be effective and stable even with reducedcontact of the framework support structure with vessel walls inproximity to the neck of the aneurysm. In embodiments in which shapedleading surface 88 is substantially impermeable to fluids, leadingsurface 88 may provide effective diversion of blood flow from theaneurysm neck and reduce obstruction of the sidebranch vessels SB₁ andSB₂.

FIGS. 5A and 5B schematically show additional embodiments of animplantable device of the present invention. FIGS. 5A and 5B illustrateimplantable devices 90 comprising a framework support structure 92having a generally inverted U-shaped configuration and two anchoringlegs 94, 96 extending from the curved framework support structure alongsubstantially parallel planes spaced a distance from one another andterminating in curved distal ends.

The curved framework support structure may be substantially continuousor may be associated with a substantially continuous membrane 95 havingmicrofeatures or micro-textures or contours 96 provided along thesurface facing (proximally) toward the anchoring legs 94, 96. Contouredsurface 96 is exposed to blood flow following deployment of the deviceand functions to direct blood flow away from the neck of the aneurysmand/or down a sidebranch vessel. Microfeatures, micro-textures orcontours 96 may be formed in a fluid impermeable substrate materialusing a variety of techniques and may assume a variety ofconfigurations. A simple curved, grooved configuration is illustrated inFIG. 5A, while a more complex grooved structure is illustrated in FIG.5B. Implantable devices having these features may be sized andconfigured, as described above, to substantially cover the neck of theaneurysm, with the curved framework structure contacting the vessel wallin proximity to the aneurysm neck. Alternatively, implantable devicesincorporating microfeatures, microtextures or contours for directing anddiverting blood flow may be sized and configured to partially cover theneck of the aneurysm and may effectively redirect blood flow away fromthe aneurysm without fully occluding the neck of the aneurysm.

FIG. 6A schematically shows another embodiment of an implantable device100 of the present invention, and FIG. 6B schematically shows the deviceof FIG. 6A deployed across the neck of an aneurysm A. Implantable device100 comprises a framework support structure 102 having a generallyinverted U-shaped configuration and two anchoring legs 104, 106extending from the curved framework support structure alongsubstantially parallel planes spaced a distance from one another.Implantable device 100 additionally comprises a shaped, curved leadingsurface 103 projecting out of the plane of the framework supportstructure and configured to engage the anatomical structure of the neckof aneurysm A. Implantable devices having a shaped, curved leadingsurface may be desirable in certain circumstances to provide a moreprecise “fit” of the leading surface across the neck and opening of theaneurysm, and to engage the aneurysm distally as well as radially. Thecontour of leading surface 103 is designed to better seat andaccommodate the neck inner surface at self-centering points ofapposition.

FIG. 6C shows yet another embodiment of an implantable device 105 of thepresent invention, and FIG. 6D schematically shows the device of FIG. 6Cdeployed across the neck of an aneurysm A. Implantable device 105comprises a framework support structure 107 having a generally invertedU-shaped configuration and two anchoring legs extending from the curvedframework support structure along substantially parallel planes spaced adistance from one another. Implantable device 105 additionally comprisesan additional structure 108 that projects from a leading surface of theframework support structure or closure membrane in a direction oppositeof the extension of the anchoring legs. The additional structure may besixed and configured, as shown, for placement within an aneurysm orcavity in a deployed condition. In the embodiment illustrated in FIG.6D, the additional structure is generally conformable to the interiorsurface of an aneurysm and may, upon deployment, form a basket-likeshape. The structure may serve to retain debris or embolic materialsinside an aneurysm cavity following placement, and may additionallyserve to reinforce the aneurysm wall. The surface of the structure mayadditionally be covered and, following deployment, may serve to redirectflow away from art aneurysm. While a basket-like structure isillustrated, it will be appreciated that many different types ofreinforcing structures may be provided.

FIGS. 7A and 7B illustrate yet additional embodiments of implantabledevices 110, 110′ of the present invention comprising a generallyinverted U-shaped framework support structure 112, 112′ having aconfiguration similar to that shown in FIGS. 1B-1E and having anocclusive or semi-occlusive membrane 114, 114″ associated with thesubstantially inverted U-shaped framework structure. Anchoring legs 116,118 extend (proximally) away from the framework support structure andclosure membrane 114, aligned on substantially parallel planes. In thisembodiment, anchoring legs 116, 118 and 116′, 118′ are formed using acombination of multiple geometrical structures, such diamonds 120, 120′,triangular structures 124, 124′ and curved segments 122. Curved segments122 illustrated in FIG. 7A may be generally sinusoidal and provideflexure or bending of the anchoring legs and framework support structurelaterally, facilitating positioning of the framework support structureand closure membrane across the neck of an aneurysm having an angledentrance. Curved segments may comprise substantially S-shaped (orbackwards S-shaped) segments, as shown, and they may comprise othersinusoidal profiles.

Alternatively, in the embodiment shown in FIG. 7B, anchoring legs 116′,118′ incorporate one or more articulating joints 125 to provide flexureand rotation of the framework support structure and closure membrane.Articulating joints 125 may provide limited angular articulation of theframework support structure and proximal portions of the anchoring legsin a single direction, or in both directions from a neutral position. Aball and socket joint may be used, for example, to providemulti-directional flexing of the framework support structure and closuremembrane.

FIGS. 7A and 7B also illustrate radiopaque markers 113, 115 and 113′,115′ provided in proximity to the lateral corners of framework supportstructure 112 and distinctive radiopaque markers 121, 123 and 121′, 123′provided in proximity to the terminal (proximal) ends of anchoring legs116, 118, and 116′, 118′. It will be appreciated that additionalradiopaque markers may be provided or that radiopaque materials may beincorporated in the materials comprising the structure of theimplantable device, including a closure membrane, to provide additionalvisibility during positioning and deployment.

FIG. 8 schematically illustrates yet another embodiment of animplantable device of the present invention in a deployed condition atthe neck of an aneurysm A. In the embodiment illustrated in FIG. 8,device 130 has a configuration that accommodates and is conformable toangulation of the aneurysm neck region. The neck region angulation maybe quantified as an angle θ formed by a line N drawn on one axis acrossthe neck of the aneurysm relative to the centerline C of the parentvessel PV of the vessel bifurcation. It will be appreciated that angle θmay change when viewed from different axes crossing the neck of theaneurysm. In this embodiment, the device support structure and covetingmembrane form multiple discrete surfaces that, in combination, form agenerally angulated inverted U-shaped profile.

In the embodiment shown in FIG. 8, implantable device 130 incorporatesan elongated, generally oblong interface surface 132 defined, in part,by a perimeter structure and two adjoining side surfaces 134, 136extending proximally from interlace surface 132 generally opposite oneanother. Interface surface 132 has at least one dimension larger thanthe neck of the aneurysm and provides lateral edges 142, 144 forcontacting the neck of the aneurysm when deployed, or for contacting thevessel wall in proximity to the neck of the aneurysm. Side surfaces 134,136 may be substantially flat, as shown, or may be curved, and generallycontact the vessel wad adjacent to the aneurysm neck and between sidebranch vessels. Anchoring legs 138, 140 extend from proximal regions ofside surfaces 134, 136 and, when deployed, contact the side walls ofparent vessel PV. The anchoring legs may incorporate a flexure mechanismto facilitate positioning and placement of the device during deployment,as shown.

Implantable devices of this type may incorporate multiple angulatedcovering surfaces aligned on different planes, or curved surfaces, toprovide enhanced coverage of an opening and conformity to vessel wallsin proximity to the opening. Interface surface 132 may be curvedsubstantially along the longitudinal centerline, or along another axisto facilitate the fit over the opening. Interface surface 132 of thedevice shown in FIG. 8, is illustrated forming a curved depression, forexample. Other types of carved configurations, including convex andconcave curved configurations, as well as more complex curvedconfigurations, such as hyperbolic paraboloid curved configurations, mayalso be used. Generally matching, symmetrical “side” surfaces 134, 136,illustrated having a mesh-like configuration, may be provided havingdifferently oriented surfaces to provide enhanced contact with vesselwalls in proximity to the opening. In addition, interface surface 132and side surfaces 134, 136 may not be symmetrical with respect to anaxial centerline C of the device, with a greater interface and sidesurface area provided on one side of the axial centerline than theother. As shown in FIG. 8, for example, lateral edge 142 of interfacesurface 132 may be beneficially oriented distally with respect to theopposite lateral edge 144 following deployment.

FIG. 9 illustrates yet another embodiment of an implantable device ofthe present invention. As shown in FIG. 9, implantable device 150 mayhave an asymmetrical, generally inverted U-shaped framework support 152having, for example, a generally flat edge 154 and a tapered extendingedge 156. Implantable device 150 also incorporates a membrane 153 andtwo anchoring legs 157, 158 extending proximally from the frameworksupport and membrane when deployed and aligned on substantiallyparallel, spaced apart planes. While this simple asymmetricalconfiguration is shown and described, it will be appreciated that manyother asymmetrical configurations may be employed.

The device of FIG. 9 is shown schematically deployed in FIGS. 10A and10B across the necks of aneurysms that are offset with respect to theparent vessel. Multiple asymmetrical devices of the type shown in FIG. 9may also be used in combination across the neck of an aneurysm, such asa wide neck aneurysm, as illustrated schematically in FIG. 10C. A firstimplantable device 150 covers a distance over the neck of the aneurysm,and a second implantable device 150′ is deployed complete cover the neckof the aneurysm. This results in a nominal overlap of the devices 150,150′ in a central area and provides full coverage across the aneurysmneck. One advantage of the implantable device configuration shown inFIG. 9, as evidenced by the deployment strategies illustrated in FIGS.10A-C, is that the device may be used in different orientations, e.g. byrotating the device 180 degrees, to satisfy different coveragerequirements and may be used in combination to satisfy other coveragerequirements.

A device embodiment similar to the device illustrated in FIG. 1incorporating anchoring legs having a different configuration isillustrated in a deployed position across an aneurysm opening in FIG.11. As shown in FIG. 11, an implantable device 160 having a generallyinverted U-shaped framework support structure 162 and an occlusive orsemi-occlusive membrane 163 associated with the support structure may bedeployed across an aneurysm neck to block or redirect blood flow intothe aneurysm A. In this embodiment, implantable device 160 incorporatestwo generally triangular anchoring legs 164, 166 that extend proximallyfrom the framework support structure on substantially aligned, spacedapart planes and contact the wall of parent vessel PV along generallyopposite surface areas.

When implantable device 160 is deployed, as illustrated in FIG. 11,anchoring segments 164, 166 contact the parent vessel PV wall along asubstantial portion of their length to maintain the framework supportstructure 162 and membrane 163 in place across the neck of the aneurysm.Proximal anchoring segments 168, 169 are contoured in a deployedposition and extend out of the plane of distal anchoring segments 164,166, crossing the parent vessel PV to contact the vessel in an areasubstantially opposite and distal from the region where anchoringsegments 164, 166 contact the parent vessel PV wall. The contour ofproximal anchoring segments 168, 169 may facilitate biasing distalanchoring segments 165, 167 against the vessel wall. Additionally,configuration of the multiple anchoring segments may facilitate smoothretraction of the device into the delivery system so that repositioningmay be achieved if needed.

FIGS. 12A-12D illustrate yet another embodiment of an implantable deviceof the present invention. FIGS. 12A and 12B schematically illustrate animplantable device 200 of the present invention in a substantially flat,pre-assembled configuration (FIG. 12A) and in a folded, assembled,deployed configuration (FIG. 12B). As shown in FIG. 12A, in asubstantially flat, preassembled configuration, implantable device 200comprises a framework support structure having a modified diamond-shapedconfiguration formed by framework sides 202, 204, 206, 208 meeting atcorners 203, 205, 207 and 209. Each of the framework sides 202, 204,206, 208 has a complex, curved, tapered configuration with a firstsegment carving inwardly from a lateral corner (205, 209) aligned onlateral centerline C_(L) and joining a second segment 202, 204′, 206′,208′ that curves inwardly to meet an adjacent segment at an axial corner(203, 207) aligned on axial centerline C_(A). Framework sides 202, 204and 206, 208 are arranged in a mirror-image configuration. While corners203, 205, 207, 209 are illustrated as being angular, it will beappreciated that the corners may have a curved profile, or a yet morecomplex configuration. The framework sides 202, 204, 206 and 208 maylikewise take a variety of curved or angular configurations and may beformed integrally with one another, or separately, with separateframework sides being bonded to one another at the corners.

In the embodiment shown in FIG. 12A, anchoring segments 210, 210′ and212, 212′ are formed integrally with the framework support structure andextend from framework side segments to form anchoring legs having agenerally planar triangular structures. Anchoring legs 210, 212 eachterminate in a junction 214, 216, respectively. In this embodiment,anchoring leg extensions 218, 220, 222, 224 extend angularly fromjunctions 214, 216 and have bonding points 219, 221, 223, 225 near theirterminal ends. Extensions of terminal ends 219, 221, 223, 225 may beprovided, as illustrated in FIG. 12A, for convenient handling of thepreformed assembly and are generally removed during assembly. Theimplantable device shown in FIGS. 12A and 12B, including the frameworkstructure and the anchoring legs, may be constructed from asubstantially flat substrate by cutting, etching (or otherwise) theframework shape from a substrate sheet.

Implantable device 200 may be formed from the pre-assembled form of FIG.12A to the assembled form shown in FIG. 12B by folding the pre-assembledform along longitudinal centerline C_(L) and bringing corners 203 and207 toward one another, forming a substantially inverted U-shapedframework support structure with the corners 205, 209 arranged on thelongitudinal centerline C_(L) positioned substantially at the midline ofthe curved portion of the inverted U-shaped structure and corners 203,207 forming the proximal ends of the inverted U-shaped framework supportstructure. The curved framework support structure is designed andconfigured to contact and support tissue in proximity to an opening orcavity such as an aneurysm. Anchoring legs formed by anchoring segments210, 210′ and 212, 212′ extend proximally (when positioned at a targetsite) from the curved framework support, forming the legs of theinverted U-shaped structure. In the embodiment illustrated in FIG. 12B,the anchoring legs formed by anchoring segments 210, 210′ and 212, 212′form generally triangular structures arranged in planes that aresubstantially parallel to one another and spaced a distance from oneanother. These anchoring legs 210, 212 are designed to contact and besupported by parent vessel walls in proximity to (and generally acrossfrom) the aneurysm when the curved framework support is placed acrossthe neck of the aneurysm.

Implantable device 200 illustrated in FIGS. 12A and 12B additionallyincorporates proximal anchoring leg segments formed by joining opposingleg extensions 218, 224 and 220, 222 at proximal junctions 228, 230. Theproximal anchoring leg segments may be formed by simply joiningrespective sets of terminal ends 219, 225 and 221, 223 to one anotherusing welding, bonding or other stable fastening mechanisms. It may bedesirable, in some applications, to reduce the rigidity and surfacedimensions of the proximal junctions. FIGS. 15A and 15B illustrate onesolution for joining leg extensions using cooperating/interlockingstructures that reduce the thickness of the junction. FIGS. 15A and 15Bshow a one leg extension terminating in a ball 227, and the other legextension terminating in a mating socket 229. Other types ofmechanically mating, or locking joints may also be provided, andsuitable mechanisms for bonding mechanically mating leg extensions, suchas bonding, welding, and the like, are well known. In one embodiment,the cooperating structures used to join leg extensions may interlock aspivoting structures, providing relative rotation of the terminaljunctions of proximal leg extensions with respect to one another.

A proximal portion of the leg extensions and proximal junctions 228, 230are configured to contact the vessel wall proximally of the location ofanchoring legs 210, 212 and on different circumferential surfaces of thevessel. Using a combination of anchoring legs having different contactsurfaces along the axial length of the neighboring (e.g., parent) vesseland different contact surfaces along the circumference of the vesselgenerally provides stable anchoring of the device without damaging thevessel wall and without interfering with flow in the neighboring vessel.Both sets of anchoring legs are generally atraumatic to tissue andcontact the vessel walls over an extended surface area.

FIGS. 12C and 12D illustrate implantable device 200 in a deployedcondition placed across the neck of aneurysm A. When deployed andpositioned across the neck of an aneurysm (or another opening), theinverted, substantially U-shaped perimeter support structure andassociated closure membrane substantially cover the neck of the aneurysmand extend circumferentially to contact tissue surround both sides ofthe neck of the aneurysm, or the vessel wall adjacent the neck of theaneurysm, at locations between the lateral corners 205, 209 and proximalto the longitudinal centerline C_(L) of the device. In the embodimentsschematically illustrated in FIGS. 12C and 12D, for example, areas ofthe perimeter support structure and closure membrane proximal to thelongitudinal centerline C_(L) and distal to anchoring legs 210, 212generally contact and support tissue, including the vessel wall, locatedcircumferentially of and in proximity to the neck of the aneurysm.Anchoring legs 210, 212 contact the wall of a neighboring vessel, suchas parent vessel PV, along substantially opposite contact surface areas.Proximal anchoring leg segments extending between junctions 214, 218 and230, 228 and proximal junctions 230, 228 contact the wall of theneighboring vessel, such as parent vessel PV, in locations proximal tothose contacted by anchoring legs 210, 212 and along differentcircumferential surface areas. This embodiment provides enhancedanchoring and support of the implantable device without damaging thevessel wall structure or tissue and without impeding flow in the parentvessel or neighboring vessels.

FIGS. 13A-13G illustrate a variety of different types of membranes andcover structures. In each of these diagrams, a framework supportstructure having a modified diamond-shaped configuration formed byframework sides having a complex, curved configuration of the typeillustrated in FIGS. 12A and 12B is shown, with a mesh-like structure ormembrane provided substantially coextensive with the internal spaceformed by the framework structure. FIG. 13A shows a framework structure240 in combination with a mesh-like cover structure 241 havingrelatively large openings in the mesh-like structure arranged in arepeating diamond configuration. FIG. 13B shows a framework structure240 in combination with a mesh-like cover structure 242 havingrelatively small openings in a mesh-like structure arranged in arepeating diamond configuration. FIG. 13C shows a framework structure240 in combination with a mesh-like cover structure 243 havingrelatively small circular openings, or pores arranged substantiallyuniformly over its surface area. FIG. 13D shows a framework structure240 in combination with a mesh-like cover structure 244 havingrelatively small openings in the mesh-like structure arranged in ascreen-like configuration. FIG. 13E shows a framework structure 240 incombination with a cover structure 245 having an array of generallylinear openings with a central opening and terminus. This embodiment mayfacilitate folding and deployment of the membrane. FIG. 13F shows aframework structure 240 in combination with a cover structure 246 havingtwo arrays of perforations arranged in curves facing the lateral cornersand two arrays of generally linear perforations arranged in achevron-like configuration lacing the axial corners of the frameworkstructure. This embodiment may facilitate folding and deployment of themembrane. FIG. 13G shows a framework structure 240 in combination with acover structure 247 having two arrays of perforations arranged in curvesfacing the lateral corners and two arrays of perforations generallyfacing the axial corners of the framework structure. This embodiment mayalso facilitate folding and deployment of the membrane. It will beappreciated that many different configurations of mesh-like, perforatedand porous membrane structures may be provided.

FIGS. 14A and 14B illustrate yet another embodiment of an implantabledevice of the present invention having a membrane substantially coveringthe internal space of both the framework support structure and theanchoring legs. Implantable device 250, as shown, comprises a frameworkperimeter support structure 252 composed of four substantially similarsegments joined at longitudinal corners 254, 256 and axial corners 258,260. Closure membrane 265 substantially fills the internal space of theframework support structure and has pores 266 along contact edges withthe framework perimeter support structure 252. Enlarged pores 268 may beprovided in proximity to corners, such as at axial corners 258, 260.Implantable device 250 additionally has proximal anchoring leg segments270, 272, 274, 276 that may be joined as described above with referenceto FIGS. 12A and 12B to provide proximal anchoring leg segments lying ina different plane from the more distally located anchoring legs.

FIGS. 16A and 16B illustrate a generally inverted U-shaped frameworksupport structure 280, 290 without a membrane, incorporating anadditional frame element 281, 291 extending between lateral corners 282,284 and 292, 294 of framework support structure 280, 290, respectively.Implantable device 280 has an anchoring leg structure similar to thatillustrated and described with reference to FIG. 7A; implantable device290 has an anchoring leg structure, with proximal leg extensions,similar to that illustrated and described with reference to FIG. 12B. Itwill be appreciated that additional frame elements having many differentconfigurations may be provided to enhance the structural stability ofthe framework support structure, to provide additional attachment pointsfor membranes or radiopaque markers, or for other reasons.

While in the foregoing specification this invention has been describedin relation to certain preferred embodiments thereof, and many detailshave been set forth for purposes of illustration, it will be apparent tothose skilled in the art that the invention is susceptible to variouschanges and modifications as well as additional embodiments, and thatcertain of the details described herein may be varied considerablywithout departing from the basic spirit and scope of the invention.

We claim:
 1. A method of constructing an implantable device comprising:providing a preformed assembly having a substantially planar, generallydiamond-shaped framework structure with a longitudinal centerlinejoining two lateral areas and an axial centerline joining two end pointsof two axial areas; and bending the two end points toward one another toform a generally U-shaped framework support structure with thelongitudinal centerline substantially bisecting the framework supportstructure and two anchoring legs extending away from the U-shapedsupport structure generally opposite one another.
 2. The method of claim1, wherein bending the two end points toward one another furthercomprises: positioning a pair of lateral corners terminating each of thetwo lateral areas approximate a distal end of the device along thelongitudinal centerline; moving the two end points in the proximaldirection from the lateral corners while moving the two end points toapproach each other; and moving the two anchoring legs to extend in theproximal direction in relation to the two end points.
 3. The method ofclaim 2, wherein bending the two end points toward one another furthercomprises: measuring a width of the device between the lateral corners;measuring a length of the device between the distal end of the deviceand a proximal end of an anchoring structure of the two anchoringstructures; and bending the device such that the length of the devicemeasures longer than the width of the device.
 4. The method of claim 1further comprising: bending the two lateral areas toward one anotherwhile bending the two end points toward one another to collapse theframework to fit within a lumen of a catheter.
 5. The method of claim 4further comprising: when the framework is collapsed to fit within thelumen of the catheter, releasing the framework thereby allowing theframework to self-expand to form the generally U-shaped frameworksupport structure.
 6. The method of claim 1 further comprising:configuring the device to maintain the generally U-shaped frameworksupport structure without requiring an external force to maintain theU-shaped structure.
 7. The method of claim 1 further comprising:providing a semi-occlusive structure extending within the generallydiamond-shaped framework structure.
 8. The method of claim 7, whereinbending the two end points toward one another further comprises: bendingthe semi-occlusive structure to form a curved, U-shape.
 9. The method ofclaim 1 further comprising: positioning the axial centerline orthogonalto the longitudinal centerline.
 10. A method for constructing animplantable device comprising: providing a preformed assembly having asubstantially planar framework structure comprising a longitudinalcenterline bisecting opposite lateral corners, an axial centerlinebisecting opposite axial corners, and two anchoring structures eachcomprising a pair of anchoring segments, the anchoring structuresextending along the axial centerline on opposite sides of thelongitudinal centerline; and bending the axial corners toward oneanother to form a generally U-shaped framework support structure withthe longitudinal centerline substantially bisecting the frameworksupport structure and the two pairs of anchoring segments extending awayfrom the U-shaped support structure generally opposite one another. 11.The method of claim 10, wherein bending the two axial areas toward oneanother further comprises: positioning the lateral corners at a distalend of the device along the longitudinal centerline; moving the twoaxial corners in the proximal direction from the lateral corners whilemoving the two axial corners to approach each other; and moving the twoanchoring structures to extend in the proximal direction in relation tothe two axial corners.
 12. The method of claim 11, wherein bending thetwo axial corners toward one another further comprises: measuring awidth of the device between the lateral corners; measuring a length ofthe device between a proximal end of an anchoring structure of the twoanchoring structures and the distal end; and bending the device suchthat the length of the device measures longer than the width of thedevice.
 13. The method of claim 10 further comprising: bending the twolateral corners toward one another while bending the two axial cornerstoward one another to collapse the framework to fit within a lumen of acatheter.
 14. The method of claim 13 further comprising: when theframework is collapsed to fit within the lumen of the catheter,releasing the framework thereby allowing the framework to self-expand toform the generally U-shaped framework support structure.
 15. The methodof claim 10 further comprising: configuring the device to maintain thegenerally U-shaped framework support structure without requiring anexternal force to maintain the U-shaped structure.
 16. The method ofclaim 10 further comprising: joining the pair of anchoring segments fromone of the anchoring structures of the two of anchoring structures tothe pair of anchoring segments from the other anchoring structure of thetwo of anchoring structures.
 17. The method of claim 10 furthercomprising: positioning the two anchoring structures to form acontiguous substantially circular shape as viewed from a plane parallelto the axial centerline and the longitudinal centerline.
 18. The methodof claim 10 further comprising: providing a semi-occlusive structureextending within the framework structure between the lateral corners andbetween the axial corners.
 19. The method of claim 18, wherein bendingthe two axial areas toward one another further comprises: bending thesemi-occlusive structure to form a curved, U-shape.
 20. The method ofclaim 10 further comprising: positioning the axial centerline orthogonalto the longitudinal centerline.